Have in-mast in my Beneteau. Its a snap to use...only time it jammed was due to operator error. Our first time out, we released the main halyard while trying to put up...er...pull out the sail. Resulted in the sail sliding down and coming out of the track. It was a pain to get the boltrope into the track again, but we learned....main halyard is never touched except to tighten tension at the dock.